Whenever you're talking to somebody, and no matter what or how many witty or interesting things you say, they reply with things such as, "cool" or "yeah." They won't allow a good conversation by making it suck with their one word answers.

Debbie: "I was texting Conrad last night."
Sally: "What did you guys talk about?"
Debbie: "More like, "what did I talk about?" because he was being a conversational cockblock the whole time."